ISSN:
1572-8943
Keywords:
DSC
;
glass transition
;
heat capacity
;
melting transition
;
nanophases
;
polymers
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Polymer molecules have contour lengths which may exceed the dimension of microphases. Especially in semicrystalline samples a single molecule may traverse several phase areas, giving rise to structures in the nanometer region. While microphases have properties that are dominated by surface effects, nanometer-size domains are dominated by interaction between opposing surfaces. Calorimetry can identify such size effects by shifts in the phase-transition temperatures and shapes, as well as changes in heat capacity. Specially restrictive phase structures exist in drawn fibers and in mesophase structures of polymers with alternating rigid and flexible segments. On several samples shifts in glass and melting temperatures will be documented. The proof of rigid amorphous sections at crystal interfaces will be given by comparison with structure analyses by X-ray diffraction and detection of motion by solid state NMR. Finally, it will be pointed out that nanophases need special attention if they are to be studied by thermal analysis since traditional ‘phase’ properties may not exist.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01987478
